With the gold removed from the places I didn't want it, it was time to start the oil gilding process.
Oil gilding requires an oil based size (glue) to be applied to the glass evenly and allowed to become tacky enough to take the gold. The size I chose was 3hr size which takes three hours to fully dry and would therefore give me plenty of time to apply the gold. The size doesn't become workable straight away, and I had to wait for a couple of hours but it gave me a nice big window of opportunity to start applying the gold before the size dried. I could have probably used a faster curing size, but might have had to limit myself to doing one letter at a time.
It is important that before you apply any size to the working area, you should apply some first to a test piece. This allows you to be able to touch the test piece without worrying about making a mess of it, to see if it is ready to have the gold applied.
For the oil gild I decided to use 18ct lemon gold in transfer leaf. The lower the number of karat in gold, the less actual gold is present. Often times it is mixed with silver to make it more durable, but this also changes its brilliance. Since the oil gild produces a matt finish, I wanted something that would contrast against the water gilded 23ct gold even more. Having the gold in books of transfer leaf made handling it much easier, and I was able to pick up the pieces of tissue paper that the gold had been pressed onto and use them to apply the gold. A little amount of rubbing on the back of the tissue paper is enough to encourage the gold to stick.
After the size was dry, I dusted any loose bits of gold from the work surface and found that the 18ct gold was noticeably stronger than the 23ct gold I had previously used. Working with oil size meant that I knew when the gold had dried and it meant I knew when I could begin to work it and back it up with paint.